Ok, this unit has to be hanged from above the plant - we had wire racks and put the plants on shelves 2 and 3, with the unit hanging from shelf 1. It worked nicely. It, realistically, covers an area of about a foot by two feet with good light. We increased the viability by putting aluminum foil under the bottom rack and also having a mylar space-blanket attached around the outside of the shelving to reflect all the light back to the plants. Kept us in microgreens all winter, no probs.
Here is the Amazon description. Our unit is two years old, never given us a problem. Will include a timer so you can plug it in and have it automatically come on and turn off as desired. (Daughter says it's also helped with SAD.)
Same terms as the AeroGrow - a reasonable donation to a charity and proof of same sent to us, or cash, whichever you'd prefer. Was about £65 new.